1. Field of the Invention
This invention relates to overmolding elastomeric shapes onto a thermoplastic substrate. In one of its aspects, the invention relates to a heat exchanger tank having an overmolded gasket and a method for making the same. In another of its aspects, the invention relates to a method of overmolding an elastomeric shape onto a plastic substrate. In another of its aspects, the invention relates to a thermoplastic article having an elastomeric article mechanically adhered thereto. In yet another of its aspects, the invention relates to a nylon automotive radiator tank having means for mechanically retaining an overmolded gasket onto the tank.
2. Description of the Related Art
Over the past decade, the automotive radiator industry has progressed from using braised copper radiators to radiators having aluminum tubes and tube headers and nylon tanks. These more recent designs require an elastomeric gasket to provide a fluid-tight seal between the nylon tank and the aluminum tube header.
Typically, a separate, premanufactured gasket is secured to the header, either adhesively or by other means, and then the tube header is mechanically attached to the tank. This technique, however, is labor intensive in that a worker is required to separately assemble the gasket onto the tank. Also, separate storage facilities are required for maintaining a supply of gaskets at the assembly area.
Furthermore, the gasket affords an effective fluid tight seal only if it is properly positioned on the tank. However, with the press of time during assembly, it is difficult to accurately control the location of the gasket on the tank. Mispositioned gaskets may cause defective assemblies that have to be either reassembled at the manufacturing site or discarded. Further, defective assemblies that are not detected at the manufacturing plant may fail prematurely in the field with obvious deleterious consequences.
One solution to this problem has been to preassemble the gasket on the tank by overmolding the gasket to the tank. U.S. Pat. No. 4,559,688 issued Dec. 24, 1985 to Abu-Isa, et al. discloses an overmolded gasket adhesively bonded to a flat surface of a nylon radiator tank. This approach has not enjoyed commercial success because of economic considerations.
Thus, there remains the need for a technique for retaining an overmolded gasket on a heat exchanger or radiator tank.